Park/Neutral Switch Ground for PCM - HELP PLEASE...

[PWagon]

I'm so close to firing up my LS swap, but I need some help. I need a ground wire to my PCM (blue #34) that grounds only when in Park and Neutral (otherwise OPEN). My truck is a 1986 K5 Blazer and has the stock park/neutral safety switch, but that thing is Greek to me. I don't even know if it's possible to get a Ground connection only when in Park/Neutral. Any ideas? Pictures would be appreciated.

 

[PWagon]

I guess I am answering my own question. If anyone of you guys are looking for the exact location of a GROUND ONLY when in PARK and NEUTRAL, then here it is. Use the Orn/Blk terminal on your park/neutral safety switch. Allegedly it only provides a ground (-) signal when in park and neutral.

 

[Russell]

That'd be the one! I was a bit too slow, knew the wire color and everything, LOL

 

[BadassBlaze]

Anyone know if the switch above is the same for 87-91?

 

[Russell]

Yup, it may not be identical but the 87-91 TBI ECMs get this info from the same switch in the same place.

The wire runs from the switch over to the ECM behind the glove box. There is a big connector there (I think one side is clear and the other side is black) that connects the fuel injection harness to the dash harness for ignition, battery, SES, ALDL, P/N, brake, VSS connections etc to and from the ECM. It's the same orange / black stripe wire as mentioned above.